软-硬互层岩体节理峰前循环剪切疲劳损伤机理研究  

Fatigue damage mechanism of soft-hard interbedded rock joints subjected to pre-peak cyclic shear loading

作　　者：许彬 刘新荣[2] 周小涵 韩亚峰 刘俊 谢应坤 邓志云 XU Bin;LIU Xinrong;ZHOU Xiaohan;HAN Yafeng;LIU Jun;XIE Yingkun;DENG Zhiyun(Key Laboratory of Hydraulic and Waterway Engineering of the Ministry of Education,Chongqing Jiaotong University,Chongqing 400074,China;School of Civil Engineering,Chongqing University,Chongqing 400045,China;China Construction Second Engineering Bureau Ltd.,Beijing 100160,China;Chongqing Chuandongnan Survey&Design Institute Co.,Ltd.,Chongqing 400038,China;Department of Hydraulic Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]重庆交通大学水利水运工程教育部重点实验室,重庆400074 [2]重庆大学土木工程学院,重庆400045 [3]中国建筑第二工程局有限公司,北京100160 [4]重庆川东南工程勘察设计院有限公司,重庆400038 [5]清华大学水利系,北京100084

出　　处：《岩土工程学报》2024年第1期90-100,共11页Chinese Journal of Geotechnical Engineering

基　　金：水利水运工程教育部重点实验室开放基金项目(SLK2023A03);中国博士后科学基金项目(2023M730432);重庆市博士后特别资助项目(2022CQBSHTB1010);重庆市博士后科学基金项目(CSTB2023NSCQBHX0223);重庆市教委科学技术研究项目(KJQN202300744)。

摘　　要：三峡库区频发微小地震下岩体节理循环剪切疲劳损伤对边坡动力稳定性具有重要影响。通过室内峰前循环剪切试验和PFC2D细观数值计算,研究了考虑一阶起伏角、含水率、剪切速率、剪切幅度、法向应力及循环剪切次数影响的软-硬互层岩体节理宏细观疲劳损伤机理。研究表明:①岩体节理剪切应力-剪切位移曲线历经初始非线性压剪变形、近似线弹性压剪变形、循环剪切疲劳损伤变形、应力缓升压剪变形、应力陡升压剪变形及应力脆性跌落压剪变形六个演化阶段。②岩体节理峰值(残余)剪切强度和疲劳剪切(法向)位移在相同一阶起伏角、含水率、剪切速率、剪切幅度或法向应力下随循环剪切次增多而分别降低和增大;且其在相同循环剪切次数下随一阶起伏角或法向应力变大而分别增大和降低,而随含水率、剪切速率或剪切幅度变大则分别降低和增大。③宏细观结果总体上吻合较好,且岩体节理细观剪切疲劳损伤裂纹数量随剪切位移变化呈前期微增-陡增、中期缓增及后期陡增-缓增-陡增的发展特征,而其随循环剪切次数变化则呈前期陡增和后期缓增的发展特征。④岩体节理宏细观剪切疲劳损伤典型演化过程可概述为压密-起裂破坏、循环错动-贯通破坏及分离-啃断破坏3个渐进性发展阶段,且宏细观剪切疲劳损伤裂纹近似呈“倒U形”密集分布于岩体节理附近。The cyclic shear fatigue damage of rock joints under frequent micro-earthquakes in the Three Gorges Reservoir area has an key impact on the dynamic stability of slopes.The macro-meso fatigue damage mechanism of soft-hard interbedded rock joints is studied via the laboratory pre-peak cyclic shear tests and PFC2D meso numerical calculation considering the effects of the first-order asperity angle,moisture content,shear rate,shear amplitude,normal stress and cyclic shear number.The results show that:(1)The curve of shear stress versus shear displacement of rock joints experiences six evolution stages,i.e.,initial nonlinear compression-shear deformation,approximate linear elastic compression-shear deformation,cyclic shear fatigue damage deformation,compression-shear deformation with slowly rising stress,compression-shear deformation with sharply rising stress and compression-shear deformation with brittle stress drop.(2)Under the same first-order asperity angle,moisture content,shear rate,shear amplitude or normal stress,the peak(residual)shear strength and cumulative shear(normal)displacement of rock joints decrease and increase with the increase of the cyclic shear number,respectively.Under the same cyclic shear number,they increase and decrease with the increase of the first-order asperity angle or normal stress,respectively.Meanwhile,they decrease and increase with the increase of the moisture content,shear rate or shear amplitude,respectively.(3)The macro-meso results are in good agreement on the whole.The number of meso shear fatigue damage cracks of rock joints exhibits the development characteristics of slight increase-steep increase,slow increase and steep increase-slow increase-steep increase in the early,middle and late stages,respectively,with the change of shear displacement;and it shows the development characteristics of steep increase and slow increase in the early and late stages,respectively,with the change of cyclic shear number.(4)The typical evolution process of macro-meso shear fatigue damage of

关 键 词：软-硬互层岩体节理 峰前循环剪切试验 PFC2D细观数值计算 演化过程 疲劳损伤机理 

分 类 号：TU45[建筑科学—岩土工程]